ABSTRACT (MICROSCOPY CORE) The overall goal of the Microscopy Core is to provide IDRC investigators with effective access to advanced methods of light microscopy, particularly the powerful new techniques of intravital microscopy developed during the previous grant period. The Microscopy Core utilizes the extensive facilities of the Indiana Center for Biological Microscopy (ICBM), the School of Medicine's 20 year-old core microscopy facility. The Core is equipped with three point-scanning confocal/multiphoton excitation microscopes, as well as a spinning-disk confocal microscope and multiple digital workstations supporting quantitative two- and three-dimensional image analysis. The Core is fully equipped to support intravital microscopy, providing investigators with space in a surgical suite with all necessary supplies for surgery, anesthesia, and animal monitoring. The Microscopy Core benefits not only from the extensive facilities of the ICBM, but also the reliable performance of systems that are fastidiously maintained by ICBM staff and continuously supported with manufacturers' service contracts. Specifically, the Core will apply and adapt methods of intravital microscopy that the ICBM has developed over the past 12 years to studies of the pathophysiology of diabetes and will develop and implement novel assays of protein and cell function based upon fluorescent protein biosensors, applying a combined approach of spectral and time-resolved fluorescence quantification. The Microscopy Core is Directed by Dr. K. Dunn, with Dr. R. Day serving as Associate Director. The Core leverages the expertise of a staff scientist and technician, and interfaces closely with the Islet & Physiology Core of the IDRC to ensure that tissue resources and surgical expertise are tightly integrated. The Aims of the Microscopy Core include: (1) Implementation of methods of quantitative intravital microscopy. (2) Continued development of intravital microscopy methods that will be applied to biological systems of interest to IDRC investigators, including approaches for studies of muscle and neurons in the brain. (3) Implementation of fluorescent protein biosensors for intravital and in vitro studies, including the optimization of biosensors for confocal and multiphoton microscopy, the design of viral vectors, validation of biosensor performance, optimized methods of image collection and quantitative analysis. (4) Training in the methods of microscopy and image analysis developed by the core for investigators whose needs exceed the capacity of the core. (5) Technical support for laboratories lacking microscopy expertise to utilize additional challenging techniques; e.g., fluorescent biosensor-based in vitro studies, fluorescence lifetime microscopy).